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    <title>Document</title>
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div.fixed{
    position: fixed;
    bottom: 0;
    right: 0;
    width: 0;
    border: 3px solid#73AD21;
}
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    <h1>position: fixed;</h1>
    <p>设置 position: fixed; 的元素会相对视口定位，这意味着即使页面滚动也会停留在某个位置：</p>

<div class="fixed">
    这个 div 元素设置 position: fixed;</div>
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